Rechargeable batteries generally include an electrode assembly which is formed by spirally winding sheet-shaped positive and negative electrodes and a separator serving as an insulator, or by stacking positive and negative electrodes and an insulating separator in a multi-layer structure. Leads or tabs are attached to the electrodes and to outer terminals.
Since large-capacity batteries for so-called Hybrid Electric Vehicles (HEVs) have bigger positive and negative electrodes in proportion to the size thereof, and thereby have increased resistances, they need a separate tab to maximize a current collecting area. Such a tab can connect an uncoated region of an electrode assembly with a terminal in a prismatic secondary battery.